1. Field of the Invention
This invention relates to means for displaying signals and is particularly concerned with a device which includes means whereby letters, numerals or other symbols are displayed.
2. Description of the Prior Art
Conventional signal indicators usually consist of a plurality of lamps arranged to form a pattern, with an optical system used in connection with the lamps to produce the desired reflection characteristics. The lamps are normally connected so that different signals are alternately displayed by different combinations of the lamps.
Some of the disadvantages of these conventional indicators are that they have a low light output, a considerable number of lamps are required, and there are many times when the indicators do not function properly because of lamp failure. Complicated wiring patterns are required, and there is also a possibility that, when lamp failures occur, the indicated signal will be misinterpreted. Each lamp provides a dot of light in the display of the various signals, and thus it is only practical to provide symbols or numerals of uniform color. In mist or fog, problems are encountered as a result of the poor resolution of the signal, and limitations on the size of the signal indicator are imposed by the dimensions of the lamps.
Light-transmitting fibers have been used for the display of symbols on indicator surfaces and are illustrated in German Pat. Nos. 2,126,672 and 2,245,460. However, in these arrangements, the intensity of the light issuing from the ends of the light-transmitting fibers has been insufficient both with regard to the total light intensity and also with regard to the intensity of the light within a selected angle of radiation.